The present invention concerns a system for testing a sample or samples for sterility and, more particularly, a sterility test system which significantly alleviates problems of extraneous contamination.
Many systems are available in the prior art for the testing of sterility by using a membrane filter method. In one prior art system, during production of bottles of a sterile liquid or medicament, after sterilization a number of bottles are taken at random and are dispensed into a single filter unit. After the solution has been received within the filter unit, the filter is removed and cut in half. One of the halves is introduced to a test medium that is conductive to growth of bacteria and the other half is introduced to another test medium which is conducive to the growth of mold. The filter halves are incubated and respectively inspected for bacteria and mold.
A disadvantage of the aforementioned prior art sterilization test is the necessity of opening the filter unit and cutting the filter, which steps are conducive to contamination. Another type of prior art sterilization testing system, for testing one sample at a time, is disclosed in U.S. Pat. No. 4,036,698. In this system, the liquid sample is drawn by a vacuum pump through a pair of filter canisters, thereafter the air is removed from each of the filter canisters, test media are introduced to each of the canisters and the canisters are incubated. The patent states that an alternative to using the vacuum pumping is to replace the vacuum pump with a peristaltic action pump.
The use of peristaltic pumps to feed the liquid to the canisters is disadvantageous because there can be different flow rates to each canister when such peristaltic pumps are utilized. Further, the types of peristaltic pumps required are expensive. The use of a vacuum pump to draw the liquid into the canisters is also disadvantageous because if one of the tubes becomes occluded, all of the liquid will be rapidly drawn into only one of the canisters. Still further, the system of U.S. Pat. No. 4,036,698 has not been suggested for use with a plurality of samples.
It is an object of the present invention to provide a system for testing sterility that is inexpensive yet simple and efficient to operate.
Another object of the present invention is to provide a sterility testing system in which the sterility does not have to be broken during testing.
A further object of the further invention is to provide a sterility testing system which operates to reduce the occurrence of false positive results caused by extraneous contamination.
A still further object of the present invention is to provide a sterility testing system in which a plurality of samples may be tested for sterility simultaneously.
Other objects and advantages of the present invention will become apparent as the description proceeds.